I have always been intrigued by theatre magic. Dr Dee is famous for having created an amazing illusion when he was a student at Cambridge in the 1540s, and even now I can’t work out how he did it. He put on a play, Aristophanes’ Peace, in which an Athenian mortal flies to heaven on the back of a dung beetle basically to ask the Gods to stop the Peloponnesian war. How did Dee manage to convince the audience that he was flying around Trinity Hall on the back of a giant dung beetle? I would have real problems doing that in the Swan Theatre in Stratford.

Unless you have the mechanics that are available to productions like Chitty Chitty Bang Bang or Mary Poppins, that kind of illusion is really hard to pull off, so I am rather fascinated by Dee. On open stages like the Swan or the Globe, with no lighting effects to speak of and the audience wrapped all the way around the stage, it’s very difficult to hide the strings.

It is intriguing to wonder how Shakespeare and his company at the Globe created magic. We know they did have effects; they could create thunder, for example. But in the controlled environment of the indoor theatres like the later Blackfriars Theatre, where there was more theatre machinery around, they had a far greater control of light – and if you can control the light, you can control the effect.

When you go to a Shakespeare play you are wondering how they are going to do Banquo’s ghost in Macbeth or how Hamlet’s father is going to appear. On an open stage this kind of illusion is harder to do. Patrick Stewart played Hamlet’s ghost in the 2008 production of Hamlet with David Tennant and we created an illusion that wherever he went on the stage, smoke surrounded him. It was actually a little machine tucked up under his great coat, but it made him look as though he was floating on a cloud of smoke wherever he went.

We did a production of Macbeth with Tony Sher and Harriet Walter in 1999, and we decided at the end of the banquet scene we needed to spook the audience. As Lady Macbeth left the banquet, she picked up one of the candles from the table and as she left, suddenly all the candles on the table extinguished by themselves. In fact the witches were sitting under the table and pulled the wicks through the candles, which is why they went out. The witches then suddenly pushed all the chairs over from underneath the table and threw the table in the air and the audience were pretty shocked; I have to say that was fun.

We spend a lot of time trying to work out the very simple magic that, of course, Shakespeare’s theatre was investigating all the time.